Steel-concrete Composite Beams Research Articles

Intelligent design of steel–concrete composite beams based on deep reinforcement learning

In this work, an automated member design method is proposed based on deep reinforcement learning (DRL). Using steel–concrete composite beam design as a case study, the design procedure is conceptualized as a sequential optimization process and modeled as a Markov Decision Process (MDP). A design agent equipped with two deep neural networks, is trained using the proximal policy optimization (PPO) method to complete the complex design task of steel–concrete composite beams, adhering to the Chinese standard for design of steel structures GB50017-2017 provisions. The structural provisions are integrated into a simulated design environment, which can respond to the agent’s actions. A universal reward shaping function is introduced to guide the agent towards success and minimize material cost. The design quality and generation performance of trained PPO agent are compared with those of the Differential Evolution (DE) in 100 random training cases, 100 random testing cases, and 95 real-world engineering cases, demonstrating significant promise and reduced time consumption for automated steel–concrete composite beam design. An approach combining PPO with DE is proposed to enhance the robustness and reliability of the original agent. Finally, a brief discussion is conducted on the essence and prospects of the proposed method.

The Influence of Shear Connectors in a Longitudinal Arrangement on Free Vibrations of Steel–Concrete Composite Beams

In this work, the role of longitudinal shear connectors in mitigating free vibrations of steel–concrete composite beams (SCCBs) is scrutinized utilizing an innovative finite element methodology. In the proposed methodology, partial shear connection between the adjacent sub-beams is considered, and the SCCBs with various stiffnesses are modeled under four common boundary conditions, namely, (a) simply supported ends (S-S), (b) one clamped end and one free end (C-F), (c) one clamped end and one simply supported end (C-S), and (d) clamped ends (C-C). Thereafter, successful verification of the proposed methodology’s efficacy is achieved through comparative analysis with the theoretical results. Lastly, a reasonable arrangement along this longitudinal direction of shear connectors is proposed based on the change law of the squared fundamental frequency ratio.

Machine learning prediction of steel–concrete composite beam temperatures during hot asphalt paving

Machine learning prediction of steel–concrete composite beam temperatures during hot asphalt paving

Study on the Degradation Model of Service Performance in Railway Steel–Concrete Composite Beams Considering the Cumulative Fatigue of Steel Beams and Studs Based on Vehicle–Bridge Coupling Theory

The steel–concrete composite beam, as a structural form that combines the advantages of steel and concrete, has been applied in railway engineering. However, with the increase in railway operation time, the degradation pattern of the service performance of steel–concrete composite bridges remains unclear. This paper proposes a method for calculating the long-term service performance of railway steel–concrete composite beams, considering the cumulative fatigue damage of steel beams and studs, based on the vehicle–bridge coupling theory and Miner’s linear cumulative damage criterion. The proposed method is validated using measured data from an in-service steel–concrete composite railway bridge with spans of 40 + 50 + 40 m. The calculated mid-span vertical displacement and the first two natural frequencies of the composite beam deviated from the measured results by only 2.1%, 7.7%, and 9.5%, respectively. The research results can provide a basis for extending the service life of composite beams and preventing the occurrence of safety accidents.

Experimental study of deconstructable embedded bolted shear connectors in composite beam subjected to cyclic loading

Bolted shear connectors have recently been introduced and studied as a convenient and demountable alternative for shear studs in steel-concrete composite beams. The major problem of welded studs is their undeconstructability. Bolted shear connectors make it possible to deconstruct and reuse the connection after its service life. In this study, the cyclic behavior of embedded bolted shear connectors in steel-concrete composite beams was investigated. The specimens included prefabricated concrete slabs with a square hole, which was filled with grout after assembling the concrete slab and steel section. Eight specimens were fabricated and tested to examine the effect of the bolt's diameter and strength on the cyclic behavior. To determine its behavior characteristics force-slip curves were applied. Ductility, strength degradation, and energy dissipation were the primary parameters investigated in this study. The results showed that the bolt’s diameter and strength significantly influenced the cyclic behavior of composite beams. Increasing the bolt's diameter and strength improved the connection's ductility and energy dissipation. Furthermore, doubling the bolt's cross-section increased the connection's ultimate strength by more than twice.

Development of a novel crack-resistance technique for concrete slab in the hogging moment region of continuous composite beam

Composite steel-concrete beams offer distinct mechanical advantages. However, concrete cracking in the hogging moment region limits the composite performance of the material. This study presents an innovative technique for enhancing the crack resistance of continuous steel-concrete composite beams, which involves the prestressing of the concrete slab in the hogging moment region through post-tensioning. Following the completion of the concrete slab in the sagging moment region, the prestress is released, thereby preserving pre-compression stress in the hogging moment region without the need for long-term prestressing. This technique is enhanced using uplift-restricted and slip-free connectors, which improve the efficiency of pre-stress introduction. Experimental tests were conducted on composite beams employing this novel technique, alongside numerical simulations. The results indicated that the proposed technique significantly mitigated concrete cracking in the hogging moment region. Specifically, the cracking load of the specimen using the new technique increased by 467 % compared to the traditional composite beam specimen, accompanied by a substantial reduction in both the quantity and width of cracks. Other primary mechanical performance indicators remained relatively similar; however, the new technique exhibited a 14 % increase in the ductility coefficient compared with the traditional method. Additionally, this technique influenced interface slip, moment redistribution, and strain response along the cross-section in both the hogging and sagging moment regions. The numerical results aligned closely with the experimental data, confirming their accuracy and effectiveness. The simulations provided solutions for various construction stages by incorporating different connection constitutive models with adequate precision. A parametric analysis was conducted, revealing a design method for the innovative technique.

Calculating shear lag in steel-concrete composite beams under combined compression and bending

Long and complex composite steel-concrete structures are becoming common, requiring a deep understanding of the effects induced by the simultaneous action of axial forces and bending. In fact, the axial force generated, for instance, by cable inclination in cable-supported structures can modify the stress distribution within the elements compared to bending scenarios, thereby necessitating a revision of the effective width to be utilized. Nonetheless, current design codes, including Eurocode specifications and others, lack provisions for addressing the combined effects of axial force and bending, as they are exclusively tailored for bending. This limitation can introduce design complexities, necessitating the implementation of intricate Finite Element (FE) models, which impose substantial computational loads and design efforts. The methodology proposed in this paper overcomes these challenges allowing to assess the stress distribution and resistance of composite deck at Serviceability Limit State (SLS) and Ultimate Limit States (ULS) by leveraging results obtained from standard beam models typically used by structural designers or practitioners. A comprehensive parametric analysis using nonlinear finite element models is performed to validate the developed methodology. A comparison with the Eurocode 4 formulations highlights that the proposed method provides superior accuracy in estimating peak stress in concrete slabs under combined compression and bending. Additionally, it facilitates straightforward verification at the ULS in compliance with Eurocode requirements.

An Analytical Solution of Piezoelectric Energy Harvesting from Vibrations in Steel-Concrete Composite Beams subjected to Moving Harmonic Load

An Analytical Solution of Piezoelectric Energy Harvesting from Vibrations in Steel-Concrete Composite Beams subjected to Moving Harmonic Load

Shear strength of steel-concrete composite I-beams with corrugated steel webs

Corrugated steel webs have been widely applied to steel-concrete composite beams due to their excellent shear performance. However, there needs to be adequate research on the shear behavior of steel-concrete composite I-beams with corrugated steel webs, and the proportional distribution of shear forces between concrete flanges and corrugated steel webs in composite I-beams has yet to be clarified. This paper experimentally investigates steel-concrete composite I-beams with corrugated steel webs with different shear span ratios. With the increase of the shear span ratio, the shear failure mode of the beam gradually evolves from shear-dominated to flexural-dominated, the shear capacity and structural stiffness of the beam are negatively affected, and the improvement of the shear resistance of the beam after webs buckling is gradually limited. As the primary shear component, corrugated steel webs contribute about 71 % to 92 % of the total sectional shear force. Notably, accounting for 15 % to 35 % of the shear capacity of the beam, the shear contribution of the concrete flange must also be typically considered. For the generalizability of research results, parametric studies are conducted using validated numerical models to comprehensively investigate the effects of steel yield strength, concrete strength, web thickness, web height, and shear span ratio. Afterward, an efficient analytical model considering the shear capacity of the concrete flange is proposed to estimate the shear strength of composite I-beams with corrugated steel webs. The proposed analytical model agrees satisfactorily with experimental and numerical analysis results. The research results can provide valuable support for designing and optimizing steel-concrete composite I-beams with corrugated steel webs.

Experimental and Numerical Study on the Performance of Steel–Coarse Aggregate Reactive Powder Concrete Composite Beams with Uplift-Restricted and Slip-Permitted Connectors under Negative Bending Moment

An innovative form of steel–concrete composite beam, the steel–coarse aggregate reactive powder concrete (CA-RPC) composite beam with uplift-restricted and slip-permitted (URSP) connectors, is introduced in this paper. The aim is to enhance the cracking resistance under negative bending moments, which is a difficult problem for traditional composite beams, and to make the cost lower than using ordinary reactive powder concrete (RPC). An experimental investigation of the behavior of six specimens of simply supported steel–CA-RPC composite beams with URSP connectors under negative bending moments is presented in this paper. The test results validated that the cracking load of steel–CA-RPC composite beams could be approximately three times that of the ordinary steel–concrete composite beams while the bearing capacity and stiffness are almost the same. A numerical model, using the concrete damaged plasticity (CDP) model to simulate the behavior of the CA-RPC material, was proposed and successfully calculated the overall load–displacement relationship of the composite beams with sufficient accuracy compared with the experimental results, and the distribution of cracks and the failure mode of the beams could also be captured by this model. Furthermore, a parametric analysis was carried out to find out how the application of prestress, CA-RPC, and URSP connectors could affect the cracking resistance of the composite beams, and the results indicated that using CA-RPC and prestress made the main contributions and that the usage of URSP could boost the effect of the other two factors. The plastic resistance moment of the beams was also compared with the calculation results using the methods introduced in Eurocode 4, and it was proved that the calculation results were lower than the experimental results by approximately 10%, which meant that the method was reliable for this kind of composite beam.

Experimental and Numerical Study of Steel-Concrete Composite Beams Strengthened under Load.

This study analysed the strengthening process of a classical steel-concrete composite beam. The beam consisted of a reinforced concrete slab connected by shear studs to an IPE steel profile. The key idea was that the composite beam was strengthened under load. This process simulated an actual reinforced structure that is always subjected to dead loads, with possible service loads. This study assumed that strengthening was implemented to increase the load-carrying capacity and stiffness, not as a way for simulation a repair. The strengthening consisted of expanding the steel part of the beam by welding an additional plate to the bottom flange of the IPE profile. This study included the results of numerical analyses conducted in Abaqus software and lab results. A three-dimensional numerical model was created, taking into account the non-linear behaviour of concrete and steel, the susceptibility of the composite at the joint plane, and the residual stresses created during welding. A full-scale strengthening of the composite beams under load was carried out. Comparison of the results obtained in the experimental tests and numerical analyses showed a very high convergence of the results, as well as in terms of the non-linear operation of steel and concrete. This confirmed the validity of the created numerical model, which can be the basis for further research into the process of optimal strengthening of composite elements.

Shear strength and ductility of novel steel fibre-reinforced concrete dowel connections for composite beams

In this paper, a novel steel fibre-reinforced concrete (SFRC) dowel connection without traditional steel bar reinforcement is proposed for steel-concrete composite beams. Push-out tests on thirty-six specimens were conducted to investigate the shear strength and ductility of SFRC dowel connections with varying dowel sizes, concrete densities, fibre content and type. Even without the presence of reinforcing bars, the SFRC dowels were able to resist substantial loads and maintained a ductile load-slip behaviour. The shear strength of SFRC dowels increased with an increase in the fibre content, dowel size, and concrete density. Further, dowels with higher steel fibres content exhibited enhanced ductility, displaying a near elastic-plastic load-slip behaviour, with an ability to resist up to 80 % of the ultimate load even at 6 mm slip. A unique analytical model to predict the ultimate load and the load-slip curve is proposed in this study. The model was able to predict the ultimate load to within 6 % of test results, on average, while the mean load at 6 mm slip was predicted to within 3 % of the test results, with standard deviation of 17 % and 13 % respectively. The general shape of the load-slip curve was also well predicted. The study also proposes simplified equations, which predicted the shear strength of SFRC dowels to within 2 % of the test results with a standard deviation of 13 %.

The analysis for fatigue caused by vibration of railway composite beam considering time-dependent effect

The time-dependent effects in steel-concrete composite beam bridges can intensify track irregularities, subsequently leading to amplified train-bridge coupling vibrations. This phenomenon may increase the stress amplitudes in the bridge steel, thereby impacting the fatigue performance of the composite structures. This paper employs multiple rigid body dynamics to construct a high-speed train model and utilizes the finite element method to develop a steel-concrete composite beam element model that accounts for time-dependent effects, interfacial slip, and shear hysteresis. This approach enables the computational analysis of the train-bridge coupling system, facilitating an investigation into the influence of concrete’s time-dependent effects on the fatigue performance of railway steel-concrete composite bridges. Focusing on a 40-m simply supported composite bridge, the train-bridge coupling dynamic responses were computed for each operational year within a decade of the completion of construction. Applying the P-M linear fatigue damage accumulation theory, statistical analysis of stress history data across various operational periods was conducted to quantify the fatigue damage induced by a single eight-car high-speed train on the lower flange of the mid-span steel beam and the beam-end studs. The findings reveal that the beam-end studs sustain greater damage than the mid-span steel beam. Moreover, the detrimental impact of time-dependent effects diminishes with the increase of operational years. Notably, compared to the initial year, the fatigue damage to the lower flange of the mid-span steel beam by an eight-car train in the tenth year has surged by 39.3%. Conversely, the damage to the beam-end studs has decreased by 47.5%.

Study on Vibration and Noise of Railway Steel–Concrete Composite Box Girder Bridge Considering Vehicle–Bridge Coupling Effect

A steel–concrete composite beam bridge fully exploits the mechanical advantages of the concrete structure and steel structure, and has the advantages of a fast construction speed and large stiffness. It is of certain research value to explore the application of this bridge type in the field of railway bridges. However, with the rapid development of domestic high-speed railway construction, the problem of vibration and noise radiation of high-speed railway bridges caused by train loads is becoming more and more serious. A steel–concrete composite beam bridge combines the tensile characteristics of steel and the compressive characteristics of concrete perfectly. At the same time, it also has the characteristics of a steel bridge and concrete bridge in terms of vibration and noise radiation. This feature makes the study of the vibration and noise of the bridge type more complicated. Therefore, in this paper, the characteristics of vibration and noise radiation of a high-speed railway steel–concrete composite box girder bridge are studied in detail from two aspects: the theoretical basis and a numerical simulation. The main results obtained are as follows: Relying on the idea of vehicle–rail–bridge coupling dynamics, a structural dynamics analysis model of a steel–concrete combined girder bridge for a high-speed railroad was established, and numerical program simulation of the vibration of the vehicle–rail–bridge coupling system was carried out based on the parametric design language of ANSYS 18.0 and the language of MATLAB R2021a, and the structural vibration results were analyzed in both the time domain and frequency domain. By using different time-step loading for the vehicle–rail–bridge coupling vibration analysis, the computational efficiency can be effectively improved under the condition of guaranteeing the accuracy of the result analysis within 100 Hz. Based on the power flow equilibrium equation, a statistical energy method of calculating the high-frequency noise radiation is theoretically derived. Based on the theoretical basis of the statistical energy method, the high-frequency noise in the structure is numerically simulated in the VAONE 2021 software, and the average contribution of the concrete roof plate to the three acoustic field points constructed in this paper is as high as 50%, which is of great significance in the study of noise reduction in steel–concrete composite girders.

Performance of Composite Steel-Concrete Beam with Stiffener next to Web Opening

Abstract Openings are provided in Composite steel-concrete beams (CB) for the allowance of ducts and pipes, which generally reduces the beam's flexural performance. So, to retain the strength of these beams, stiffeners are introduced adjacent to the web openings. Hence, a numerical study is performed to evaluate the influence of the stiffeners next to web openings through finite element analysis (FEA) software ABAQUS v6.14. Three different shapes of openings with three different placements of stiffeners are considered for the study, namely circular, rectangular, and triangular openings with stiffeners along longitudinal, transverse, and diagonal directions. As revealed from the findings of FEA, comparisons are made based on the ultimate load, stiffness, and stress distribution. From comparisons, it is found that double-sided longitudinal and transverse stiffeners next to the circle opening are comparable to conventional CB. Similarly, Diagonal stiffeners increase strength in rectangular and triangle openings. Transverse stiffeners failed to increase load capacity and decrease stress concentration compared to other longitudinal and diagonal stiffeners. Further validation for the finite element results is done using the Levenberg-Marquardt (LM) algorithm, using the backpropagation variant technique of Artificial Neural Network (ANN). The results of ANN, i.e., Mean Square Error (MSE) and Multiple Determination Coefficient (R2), are above 0.9 and below 1, respectively. Thus, the results of ANN indicate that the provided results are perfectly fit for predicting with the ANN technique.

Shear Performance of Prefabricated Steel Ultra-High-Performance Concrete (UHPC) Composite Beams under Combined Tensile and Shear Loads: Single Embedded Nut Bolts vs. Studs

Ultra-high-performance concrete (UHPC) is widely used in precast concrete-steel composite beams because of its beneficial properties, including reduced structural weight, higher flexural rigidity, and reduced tensile crack formation. In comparison to conventional steel-concrete composite beams, steel-UHPC composite beams exhibit superior characteristics, including reduced structural deadweight, enhanced flexural stiffness, and the capacity to withstand tensile cracking. One successful attempt at meeting the current demands for expedited girder engineering is the development of steel-UHPC composite beams with full-depth precast slabs as key components affecting the overall structural performance using dismountable single embedded nut bolts (SENBs) and widely used studs as competitive alternatives. In contrast, shear connectors are exposed to a combined tensile and shear stress in service life rather than shear only. The corresponding scientific problem is the problem of combined effects under stress in practical applications, but there is currently no relevant research. The shear performance of SENBs in precast steel-UHPC composite beams under tension and shear loads remains unclear. For this purpose, ten push-out specimens and theoretical analyses were performed in this paper, considering the influence of the connector’s type and tensile-to-shear ratio. However, ten specimens were conducted to investigate the tensile-to-shear ratio, and the connector’s type on shear performance is limited. In the future, an increasing number of specimens and test parameters should be considered to investigate the shear performance of precast steel-UHPC composite beams. An increase in the tension-to-shear ratio resulted in a substantial reduction in the ultimate shear capacity, initial shear stiffness, and ductility of the studs. The increase in the tensile-shear ratio from 0 to 0.47 resulted in a 16.9% decline in the ultimate shear capacity, a 30.4% reduction in the initial shear stiffness, and a 21.7% decrease in the ductility of the Series I samples. However, an increase in the tensile-to-shear ratio of the Series II samples from 0 to 0.47 resulted in a 31.3% decline in ultimate shear strength, a 33.2% decline in initial shear stiffness, and a 41.9% decline in ductility. The SENBs demonstrated minimal deviations in ultimate shear capacity compared to their stud counterparts, despite exhibiting notable differences in shear stiffness, and ductility. A lower tensile-to-shear ratio was recommended in practical engineering, which might achieve a larger ultimate shear capacity, stiffness, and ductility. The design-oriented models with enhanced applicability were developed to predict the tension-shear relationship and the load-slip curve of SENBs in prefabricated steel-UHPC composite beams subjected to combined tensile and shear loads. For a tensile-shear relationship model, the point error range was 0 to 0.08, with an average error of 0.03. The square coefficient (R2) was 0.99 for a load-slip curve model. The study findings could offer a credible reference for the shear mechanism of such economical and environmentally friendly precast steel-UHPC composite beams in accelerated bridge construction.

Prestressed CFRP Plates and Tendon Strengthening of Steel–Concrete Composite Beams

This study aims to enhance the ultimate capacity and stiffness of steel–concrete composite beams through external strengthening with prestressed carbon fiber-reinforced polymer (CFRP) plates and post-tensioned CFRP tendons. A 3D finite element model was developed using ANSYS and validated using experiments. The impact of various parameters on the capacity of the beam was investigated, including the level of post-tensioning in the CFRP tendons, tendon profile, degree of shear connection, and beam load level when adding strengthening CFRP tendons. Results indicate that reinforcing composite beams with bonded CFRP plates using post-tensioning tendons with trapezoidal and parabolic profiles can increase maximum load capacity by 37% and 60%, respectively, while maintaining high stiffness. This study also indicates that the optimal strengthening conditions for the composite beam are when the beam is loaded up to 70% of its capacity and has a composite action degree of 100%.

Restoration of load capacity and stiffness of continuous steel–concrete composite beams having web openings using externally applied FRP strips

AbstractThe aim of this study is to explore the applicability of externally bonded fiber‐reinforced polymer (FRP) composites to enhance the structural performance of steel–concrete composite beams with web openings in terms of load capacity and stiffness. In order to achieve this aim, the ABAQUS software was used to create a three‐dimensional (3D) non‐linear finite element model (FEM) to simulate the behavior of FRP‐strengthened continuous composite beams with web openings exposed to monotonic loadings. After ascertaining the accuracy of the proposed model's results in successfully predicting failure patterns and load capacities of the experimentally tested specimens available in the literature, the suggested model was used to create a parametric study. The parametric study focused on the impacts of the opening location, opening shapes, and opening area on the failure pattern, load carrying capacity, and stiffness of continuous steel–concrete composite beams. Additionally, strengthening the web openings using different configurations and lengths of FRP strips with and without bolts was investigated. Results showed that the presence of web openings in location 2 exhibited the lowest load capacity of all investigated beams (20.80%–42.50% lower than the control composite beam). Moreover, the continuous composite beams with a circular opening were the best case and gave a higher failure load as compared to the rectangular opening at all locations. Additionally, all the simulated FRP‐strengthened composite beams in the third group demonstrated significant values of load capacities and stiffness among all the analyzed specimens.

Modeling of innovative bolted shear connectors in demountable cold-formed steel-concrete composite beams: Validation of finite element model and parametric study

Composite cold-formed steel (CFS)-concrete structures have been widely used due to their benefits such as more ultimate strength, stiffness, and postponement of lateral buckling compared to bare CFS steel. Appropriate shear connectors should be used in order to establish composite performance between the CFS section and the concrete component. Traditional welded-stud connectors cannot be used due to the low thickness of the CFS members. Therefore, in this paper, a novel composite connection consisting of bolted-shear connectors embedded in grout is proposed and its performance is investigated by numerical models of push-out tests. A three-dimensional finite element model of the composite connection considering the non-linearities of the material and geometry, interfaces, and interactions between the components and materials are developed and verified against the results of the experimental study. After that, an extensive parametric study is carried out and the effects of different parameters, such as bolt strength and diameter, CFS section thickness, concrete compressive strength, and pretension load on the structural behavior of this type of composite connection are investigated and discussed in detail. It is concluded that the behaviour of the composite connection is significantly influenced by bolt strength and diameter, CFS section thickness and strength. The available design models provided in different provisions, including AISI, EC4 and AISC that predict the shear load capacity of connections with preload bolted shear connectors are reviewed and assessed. The results show that the ultimate shear load capacity values predicted by these provisions were found to be relatively less accurate. Finally, a new and more accurate design equation based on the results of this study is then proposed.

Numerical simulation of steel-concrete composite beams and slabs at elevated temperatures

Steel-concrete composite beams with shear studs providing composite action between the concrete slabs and steel beams are widely used in modern steel-framed building construction. Three-dimensional finite element modelling has been a viable option for investigating the fire behaviour of composite beams. Although many finite element models are available in the open literature, most of them are simplified models verified by limited test data. Meanwhile, early test data often did not have all the required information for finite element simulation, and some assumptions need to be made. But more detailed test data are now available in the open literature for steel-concrete composite beams, which can be used to develop a generalised finite element model. In addition, National Institute of Standards and Technology has proposed new stress-strain models for steels at elevated temperatures, which can be compared with the more widely adopted Eurocode 4 steel material models in simulating composite beams. Accordingly, this paper selected 22 specimens, including two reinforced concrete slabs, 12 composite beams with reinforced concrete slabs, two composite slabs with profiled steel sheeting, two steel-concrete composite push test specimens with profiled steel sheeting, and four composite beams with profiled steel sheeting, from nine references to verify the developed finite element model. The proposed finite element model can capture different failure modes of composite beams, such as steel yielding/local buckling, concrete cracking/crushing, debonding of profiled steel sheeting, and stud fracture, which is crucial to comprehend the composite beam behaviour at elevated temperatures.